Feed Element Research Articles

Uptake of heavy metals and arsenic in black soldier fly (Hermetia illucens) larvae grown on seaweed-enriched media.

The black soldier fly (Hermetia illucens) is one of the most promising insect species for use in animal feed. However, studies investigating feed and food safety aspects of using black soldier fly as feed are scarce. In this study, we fed black soldier fly larvae feeding media enriched with seaweed, which contains naturally high concentrations of heavy metals and arsenic. The aim of this study was to investigate the potential transfer of such undesirable substances from the feeding media to the larvae. The larvae accumulated cadmium, lead, mercury and arsenic. Concentrations of these elements in the larvae increased when more seaweed was added to the feeding media. The highest retention was seen for cadmium (up to 93%) and the lowest for total arsenic (up to 22%). When seaweed inclusion exceeded 20% in the media, this resulted in larval concentrations of cadmium and total arsenic above the current European Union maximum levels for these elements in complete feed. Our results confirm that insect larvae can accumulate heavy metals and arsenic when present in the feeding media. A broader understanding of the occurrence of these undesirable substances in processed larvae products is needed to assess feed and food safety. © 2017 Society of Chemical Industry.

Bandwidth improvement of a rear end slot antenna on a Substrate Integrated Waveguide cavity

A technique for enhancing the bandwidth of the planar slot antenna on the substrate integrated waveguide cavity has been discussed in this paper. Planar slot antennas are extensively used in research because of its simple profile and moderate gian. Inspite of employing a planar rectangular slot which results in a narrow bandwidth, a broadband slot can be used to improve the bandwidth. This slot antenna is been placed at the rear end of the substrate integrated waveguide and excited by 50Ω grounded coplanar waveguide to provide good isolation. The substrate integrated waveguide adopts the mm wave technology and it facilitates the feeding element and the antenna to be built on the same substrate. The return loss is obtained as -30 dB and -22 dB at 10GHz and impedance bandwidth of 1.98% and 9.9 % for the rectangular slot and the broadband slot respectively. Further the performance is analysed by varying the height of the substrate, the length and width of the slot. The benefits of the antenna include simple profile, low weight, easy fabrication and integration with planar circuits.

Yagi–Uda nanoantenna For NIR domain

Single component metal nanoparticles, such as Ag and Au, have surface plasmon resonance wavelengths in the visible region having a weak dependence on particle size. For double component (core/shell) nanoparticles, by proper tuning the core size and shell thickness, a wide variation in optical radiation characteristics as well as in surface plasmon resonance wavelength up to Near-Infrared (NIR) region can be achieved. These aspects encourage one to model an optical Yagi–Uda antenna adopting core/shell nanoparticles as feed element, reflector and directors. In this paper, adopting the COMSOL Multiphysics software, we design all core/shell Yagi–Uda nanoantennas in the NIR domain. $$\hbox {SiO}_{2}/\hbox {Au}$$ core/shell nanoparticles are taken as antenna elements for the proposed antenna, whose surface plasmon resonance wavelength can be shifted to the NIR region by tuning the core to shell size ratio in a particular size band. The optimized directivity and gain for this antenna is achieved with only one reflector and one director, thus making it ultra-compact, cost-effective and simple in structure. This type of very highly directional Yagi–Uda nanoantenna can be used in medical science such as in targeted drug delivery and in wireless optical communication.

Analytical method of pattern analysis for cluster-fed reflectors with random feed displacements

ABSTRACTAn innovative analytical method for the evaluation of the directivity patterns of cluster-fed reflector antennas with random feed element position and orientation displacements is presented. In this approach, the sensitivities of the incident magnetic field, far electrical field and directivity are derived with respect to the feed element position and orientation displacements. The effect of random position and orientation displacements on the directivity pattern is investigated via the numerical characteristics of the directivity with pre-calculated sensitivities; meanwhile, the upper and lower bounds of the directivity pattern are illustrated. A seven-element cluster-fed offset reflector is utilised as a numerical example to show the application of this method with different feed element position and orientation displacements. Comparison with the Monte Carlo method demonstrates the effectiveness and applicability of the proposed method.

On the development of Antenna feed array for space applications by additive manufacturing technique

Space agencies are looking for advanced technologies to build light weight and stiff payload components to bear space environment and launch loads. Additive manufacturing (AM) techniques like Direct Metal Laser Sintering (DMLS) is one of the suitable option which can be explored for space applications. This paper highlights the development process of Antenna Feed Array (AFA) using DMLS as an Additive Manufacturing (AM) technique. A high efficiency horn element is used in the array. Such horns are preferred for this development as they are the prime choice for feed elements in High Throughput satellites (HTS) that employ Multibeam Antennas. A brief description of Multibeam antennas along with the RF design process for the high efficiency horn is presented. In the development process, certain design rules of AM are adopted based on consideration to produce self-sustaining structures. AFA realized by DMLS is evaluated by functional testing, vibration testing for space qualification test levels. Test results shows its structural intactness which proves its space worthiness. Procedures are very well established for further development of space payload components.

Biased Nanoscale Contact as Active Element for Electrically Driven Plasmonic Nanoantenna

Electrically-driven optical antennas can serve as compact sources of electromagnetic radiation operating at optical frequencies. In the most widely explored configurations, the radiation is generated by electrons tunneling between metallic parts of the structure when a bias voltage is applied across the tunneling gap. Rather than relying on an inherently inefficient inelastic light emission in the gap, we suggest to use a ballistic nanoconstriction as the feed element of an optical antenna supporting plasmonic modes. We discuss the underlying mechanisms responsible for the optical emission, and show that with such a nanoscale contact, one can reach quantum efficiency orders of magnitude larger than with standard light-emitting tunneling structures.

Resonant cavity‐based dielectric lens antenna for 60 GHz‐band wireless applications

A resonant cavity-based dielectric lens antenna has been presented for 60 GHz-band (57.24–65.88 GHz) wireless applications. The feeding element is a patch antenna designed with size improvement method for laboratory based fabrication with printed circuit board etching process. A semi-sphere dielectric lens is placed in front of the feeding antenna at a distance equal to about half-wavelength of the operating central frequency of 61 GHz. Simulation analysis has been performed on the cavity height and lens radius to obtain an optimised antenna design for its best performance in term of gain (20.1 dBi) and return loss (S 11) bandwidth (6.14 GHz).

New vibroscreen with additional feed elements

The article presents research results of the screening process of bulk materials with a new vibroscreen design with additional feed elements. Changes of the traditional screen structure is shown, the use of them increases the screening process efficiency and passage intensity of lower grade of bulk material to the sieve. It is established that the most simple, accessible, effective and efficient way to increase the effectiveness of the screening is the use of additional feed elements.According to the developed mathematical model of cell screening process, numerical studies to identify the effect of process parameters on the screening kinetics carried out. It is proved that the use of additional feed elements has a significant effect on the screening process kinetics and the state evolution of fine particle concentration in the bulk layer. It increases the screening effectiveness by improving the sieve filling and reduces the screening time. It is proved the performance, possibility to use, benefits, efficiency, and prospects for further research of the new vibroscreen scheme with feed elements.Description and results of comparative experimental studies of vibroscreens with different variants of additional bulk material excitation are presented.

A single-sided meandered-dual-antenna structure for UHF RFID tags

A meandered-dual-antenna structure is proposed for UHF radiofrequency identification (RFID) tag. It is composed of two independent antennas printed on the one side of the substrate board. One of the antennas is exclusively used for receiving and harvesting sufficient energy to the tag chip having the complex conjugate impedance of the receiving antenna. The other is for backscatter to enhance maximum differential radar cross-section with purely real input impedance, to enhancement the read range. The receiving antenna is formed by a rectangular loop and a parasitic meandered line. The rectangular loop is used as a feeding element for the meandered line. The backscattering antenna is made using a meandered dipole along with a thin rectangular strip. The input impedance of the receiving antenna is designed to be conjugate matched to the chip impedance (13.5-j110 Ω), whereas the input impedance of backscattering antenna alternatively switched to open and short circuit for modulating the backscattered field. The input impedance of receiving and backscattering antennas is measured using differential probe technique. The simulated and measured results are found in good agreement. It is also demonstrated that the read range of UHF RFID system increased considerably by using the dual-antenna structure.

High gain CP aperture-coupled antenna for X-band application

In this paper, we present a composite feed circularly polarised aperture-coupled microstrip antenna at X-band with improved characteristics. The feed element is intended to produce right-hand circular polarization (RHCP). Along the periphery of the circular patch, two notches are cut at diametrically opposite points. The dimension of these diametrically opposite notches determines the AR. A prototype antenna has been designed, built-up and experimentally measured which allows the analysis and discussion about different characteristics of the antenna. The simulated 2:1 VSWR bandwidth is about 2.33 GHz (c GHz). The measured 3-dB AR bandwidth is about 1.7 GHz (8.7–10.4 GHz) and the centre frequency of the impedance bandwidth is 9 GHz which agrees with the simulation result. It is revealed by experimental results that the designed antenna achieves about 19% axial ratio bandwidth as much as 8.7 dBi gain.

A scoping review of enteral feeding protocol in critically ill children

Objective To conduct a scoping review to systematically review the literature reporting enteral feeding protocol in critical ill children. And extract elements of enteral feeding protocol. Methods The database of BIOSIS Previews, PubMed, MEDLINE, EMbase, China Biology Medicine Disc, China National Knowledge Infrastructure and Wan Fang data were searched. Data were extracted on the information of article, elements of enteral feeding, evaluation of feeding etc. Results Three historical controlled studies, three case-control studies, two cohort studies, one narrative review and one qualitative study were included. Totally 16 elements were got, such as nutrition evaluation, estimated energy requirement, contraindication, feeding intolerance etc. And all protocols defined advancement and feeding intolerance. Conclusions Enteral feeding protocol has been used in most PICUs to optimize nutrition. But we observed variability in the composition of protocols and lack of evidence-based recommendations in few elements. Key words: Enteral feeding protocol; Critical ill children; Scoping review

NEW METHOD OF REFLECTOR SURFACE SHAPING TO PRODUCE A PRESCRIBED CONTOUR BEAM

In this paper a simple iterative synthesis method is presented for the formation of the shape of the reflector surface with a single feed element to produce the desired contour beam. This is the method of the optimal phase synthesis of the appropriate field in the reflector aperture similar to other works. But unlike them, we solve the problem in a very simple way using the properties of complex-valued functions and Fourier transforms and not applying complicated methods of numerical minimization theory.

Investigation of a Loop Antenna as a Feed Element for Parabolic Reflectors Using the Body of Revolution Approach

A recently published technique that is based on the body of revolution approach is applied in this paper to investigate the radiation characteristics of a circular loop antenna as a feed element of a small parabolic reflector. The study shows that, a small parabolic reflector antenna of diameter 0.3 m that is fed by a resonant circular loop at 2.4 GHz can be designed to give a directivity of 12.75 dB with reflection coefficient less than -28 dB based on 75Ω line. The H- and E-plane HPBWs of the antenna are 29.8º and 37.8º respectively. Moreover, the current density on the surface of the loop feed reflector is computed using the body of revolution approach. Keywords: Bodies of revolution, circular loop antennas, feed elements, loop feed reflector, parabolic reflector, radiation pattern.

ELECTROLYTES – SODIUM, POTASSIUM AND CHLORIDES IN POULTRY NUTRITION

Sodium, potassium and chlorides play a crucial role in maintaining body acid-base balance as well as osmotic pressure in body fluids. These processes are the result of synergetic action of all three elements, and the role of each individual component is diffi cult to defi ne without knowing and taking into consideration the other two elements. The maintenance of this value is determined by three major factors – balance and ratio ofelectrolytes in feed, endogenous acid production and level of renal activity. Electrolyte imbalance is quite rare, since body’s buff ering system provides maintenance of normal physiological pH value. Th is article will give an overview of the role, importance and needs of poultry for sodium, potassium and chlorides, as well as occurrences related to defi cit and the imbalance of those elements in feed.

Uptake of Cadmium, Lead and Arsenic by Tenebrio molitor and Hermetia illucens from Contaminated Substrates.

Insects have potential as a novel source of protein in feed and food production in Europe, provided they can be used safely. To date, limited information is available on the safety of insects, and toxic elements are one of the potential hazards of concern. Therefore, we aimed to investigate the potential accumulation of cadmium, lead and arsenic in larvae of two insect species, Tenebrio molitor (yellow mealworm) and Hermetia illucens (black soldier fly), which seem to hold potential as a source of food or feed. An experiment was designed with 14 treatments, each in triplicate, per insect species. Twelve treatments used feed that was spiked with cadmium, lead or arsenic at 0.5, 1 and 2 times the respective maximum allowable levels (ML) in complete feed, as established by the European Commission (EC). Two of the 14 treatments consisted of controls, using non-spiked feed. All insects per container (replicate) were harvested when the first larva in that container had completed its larval stage. Development time, survival rates and fresh weights were similar over all treatments, except for development time and total live weight of the half of the maximum limit treatment for cadmium of the black soldier fly. Bioaccumulation (bioaccumulation factor > 1) was seen in all treatments (including two controls) for lead and cadmium in black soldier fly larvae, and for the three arsenic treatments in the yellow mealworm larvae. In the three cadmium treatments, concentrations of cadmium in black soldier fly larvae are higher than the current EC maximum limit for feed materials. The same was seen for the 1.0 and 2.0 ML treatments of arsenic in the yellow mealworm larvae. From this study, it can be concluded that if insects are used as feed materials, the maximum limits of these elements in complete feed should be revised per insect species.

Simulation modeling of functional adaptive interference nulling for multibeam hybrid reflector antenna systems

This paper considers the simulation of adaptive nulling mechanism patterns in hybrid reflector antenna systems with a 19-element feed element, in which the radiation pattern is formed as a cluster. Incidents of broadband and narrowband interference are studied in the article.

Heterochrony in Two Sculpins of the GenusPsychrolutes: Growth Outpaces Skeletal Development in an Apex Predator among Ichthyoplankton

In fishes, development is a plastic process, even among closely related, sympatric taxa. Selective pressure manifests itself through morphological divergences in early life. Of particular interest in the present study is heterochrony: alterations in developmental rates of change. Examinations of skeletal development in the Soft Sculpin, Psychrolutes sigalutes, and Tadpole Sculpin, Psychrolutes paradoxus, revealed marked developmental differences between species. While P. paradoxus quickly develops an adult skeleton and settles in adult habitat, P. sigalutes undergoes a remarkably protracted transformation (the transition from larval to juvenile characters) over a period of three to four months. It reaches sizes in excess of 40 mm (75% of adult size) before settling. While the earliest phases of life focus on the development of feeding elements and a transition from larval/anguilliform locomotion to caudal/subcarangiform propulsion, the two species diverge quickly in postflexion development. With the excep...

Analysis of 22 Elements in Milk, Feed, and Water of Dairy Cow, Goat, and Buffalo from Different Regions of China.

The objectives of this study were to measure the concentrations of elements in raw milk by inductively coupled plasma-mass spectrometry (ICP-MS) and evaluate differences in element concentrations among animal species and regions of China. Furthermore, drinking water and feed samples were analyzed to investigate whether the element concentrations in raw milk are correlated with those in water and feed. All samples were analyzed by ICP-MS following microwave-assisted acid digestion. The mean recovery of the elements was 98.7% from milk, 103.7% from water, and 93.3% from a certified reference material (cabbage). Principal component analysis results revealed that element concentrations differed among animal species and regions. Correlation analysis showed that trace elements Mn, Fe, Ni, Ga, Se, Sr, Cs, U in water and Co, Ni, Cu, Se, U in feed were significantly correlated with those in milk (p<0.05). Toxic and potential toxic elements Cr, As, Cd, Tl, Pb in water and Al, Cr, As, Hg, Tl in feed were significantly correlated with those in milk (p<0.05). Results of correlation analysis revealed that elements in water and feed might contribute to the elements in milk.

Structure crop rotations and soil fertility tsenralnoy of zone Forest Steppe

It is rotined that in the modern terms of management in default of stock-raising and manure indemnification of elements of feed takes place due to uncommodity part of harvest, that is considered as biologithation of crop rotations. In 5 field crop rotations with a pea and herbares without top-dressing returning all uncommodity part, provides complete indemnification of makroelements feeding on potassium, and on nitrogen and phosphorus bal­ ance was negativ. At top-dressing in uncommodity part of harvest there was sufficient number of elements of feed for achievement of positive balance on nitrogen and phosphorus, and in medial 1 ga of crop rotation retorn: 22 kg of nitrogen, 33 kg of phosphorus and 102 kg of potassium.

Monopulse sum and difference signals with compensation for a failed feed element

Monopulse antenna systems are commonly used in airborne radar as they give angular information in a single measurement. For amplitude based monopulse antenna systems, multiple overlapping beams are sent out from the antenna feed elements. These signals may then be re-combined using a comparator network to form the sum and difference signals, which provide angular information relating to the target position. This study investigates a proposed method by which the individual feed element signals from the monopulse antenna are captured and combined in software, thus removing the need for a hardware comparator behind the feed elements. Results of a sum and difference signal created by a comparator and by this proposed method are compared. This study then verifies a method by which the individual feed element signals from the monopulse antenna are captured, combined in software and presents a novel method to compensate for a failed feed element signal, verified in both simulation and anechoic chamber measurements. It is shown that this new compensation for a single failed feed element works well for a signal in the centre of the monopulse antenna, where gain and sum patterns are shown to be conserved.